alliance search by language
The only way you can guess about that is by asking the leader of the alliance or have a thorough look through their infopage. I cannot think out of another criteria. I may lead an alliance for awhile and speak english but go into vacation and my substitute may not speak english. What about the German or the Russian or the Romanian players? May be you should try to contact the Guides, they are experienced players and may direct you to a better selection of alliances.
"I have seen what power does, and I have seen what power costs. The one is never equal to the other." G`Kar, Babylon 5